Final answer:
The question cannot be accurately answered with the provided text excerpts as they do not mention Pi or his comparison of swimming fish; the excerpts are from different literary works.
Step-by-step explanation:
Pi, the protagonist in the novel 'Life of Pi', does not actually compare the swimming multitudes of fish to anything in the provided text excerpts. The excerpts presented focus on different characters and their experiences with water, such as Nick feeling the warm water and seeing a bass jump in 'The Sun' by Georg Trakl, but they do not feature Pi or his observations. As such, it's impossible to provide an accurate comparison from these passages. For insights on Pi's specific comparisons regarding the fish, one would need to refer to the actual text of 'Life of Pi' by Yann Martel.